1. Field of the Invention:
This invention relates in general to subsea well completion equipment, and particular to a tie-back connection apparatus for a subsea well.
2. Description of the Prior Art:
One method of completing a subsea well is to place the Christmas Tree on the subsea floor. Valves and controls will be associated with a Christmas Tree for controlling the flow of oil. The oil may flow through a production riser extending to a production platform at the surface.
A subsea Christmas Tree and its controls will be considerably more expensive than a Christmas Tree located above the surface of the water. Because of this, tie-back connections are sometimes used. With a tie-back connection, conduit is extended from the wellhead housing at the subsea floor to the surface. The Christmas Tree will be mounted at the top of the conduit at the surface. The conduit will be supported in tension by a floating production vessel.
One difficulty with existing tie-back connections is in stabbing the production riser over the wellhead housing. Typically, wellhead connectors have hydraulically actuated dogs which engage circumferential grooves formed on the exterior of the wellhead connector. This requires a hydraulic system to actuate and disengage the wellhead connector.